import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;public class DataBaseConnection {private static final String DBDRIVER = "org.gjt.mm.mysql.Driver";private static final String DBURL = "jdbc:mysql://localhost:3306/test";private static final String DBUSER = "root";private static final String PASSWORD = "admin";public Connection conn;//饿汉式数据库连接public Connection getConnection() {try {if (conn == null && conn.isClosed())Class.forName(DBDRIVER);conn = DriverManager.getConnection(DBURL, DBUSER, PASSWORD);} catch (ClassNotFoundException e) {// TODO Auto-generated catch block
            e.printStackTrace();} catch (SQLException e) {// TODO Auto-generated catch block
            e.printStackTrace();}return conn;}public void close(){if(conn != null){try {this.conn.close();} catch (SQLException e) {// TODO Auto-generated catch block
                e.printStackTrace();}}}
}

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;public class DatabaseConnection {private static final String DBDRIVER = "org.gjt.mm.mysql.Driver";private static final String DBURL = "jdbc:mysql://localhost:3306/test";private static final String DBUSER = "root";private static final String PASSWORD = "admin";private Connection conn = null;// 如果要实例化本类对象，实际上就是为了取得数据库连接，那么就把连接过程交给构造方法public DatabaseConnection() {try {Class.forName(DBDRIVER);this.conn = DriverManager.getConnection(DBURL, DBUSER, DBPASSWORD);} catch (ClassNotFoundException e) {e.printStackTrace();} catch (SQLException e) {e.printStackTrace();}}public Connection getConnection() {return this.conn;}public void close() {if (this.conn != null) {try { // 关闭时几乎不会有问题this.conn.close();} catch (SQLException e) {e.printStackTrace();}}}
}